Images: Microsoft's 3D photo album

Here, for instance, selected pictures of Paris' famed Notre Dame cathedral (left) are assembled into a 3D model around a relatively simple rendering of the facade (right), based on the position the photographer was in when each shot was taken--a puzzle the program solves using various algorithms.

Viewers use the interface (bottom) to move around the space: The program shuttles them to the next shot while providing renderings that create the illusion of a seamless environment.

Photosynth also lets its users find shots that are similar to a given photo--a historical view taken from the same vantage point, for example.

A close-up look at how the browser technology creates a 3D model by distributing the photos according to the vantage point from which they were taken. The detail in the upper right shows the village from above.

A look at the interface gives a sense of the various ways people can navigate the terrain.

Invading hordes of reflective envelopes leap a great wall. Actually, it's another 3D model.